Easy Way to Get 'Vidmaster Challenge: Classic' Achievement
Getting this Achievement which is one step along the road to obtaining the Recon Armor, requires you to complete any level on Legendary difficulty without ever using a weapon or throwing a grenade. The best level to do this on is Uplift Reserve; simply get on the Warthog at the beginning of the level and quickly drive past the Wraiths and Choppers that are gunning for you. Switch to the Ghost when you first encounter it and boost through the next few areas; if you need a new Ghost along the way grab the one that's about halfway through the level. Keep boosting through until you reach the end of the level to unlock the Achievement.